package field_method04;

public class Circle {
    double r;
    public void area(){
        double pai = 3.14;
        double s = pai*r*r;
        System.out.println("面积为："+s);
    }
    public void area2(double pai){
        double s = pai *r*r;
        System.out.println("面积为:"+s);
    }
    public double area3(double r,double pai){
        double s = pai *r*r;
        return s;
    }



}
